Electrical sound converting appa



named Feb. 1o, ma

Re. 15,993v

y UNiTEo PATE-Nur oF-sicu.'

lui...r1r1'1i. nao1r, or m man, manteau.

Imuacrriiliic'AL sounnconvim'nne APPARATUS.

origini no..l1,4e1,'lzos,fdatu nu 22, 1924, smal no. 579,283, ined August 2, 1922. Applicata m To all wlzomt may concern ,Be it known that l, CHARLES Pn'rxnisoN. a citizen of wthe United States,v and 4re y may also be used asa telephone transmitter.`

The objects` of` my invention yprovide an electromagnetic operating systemv '-0 for sound reproducing or converting apparatus, in which the ellciency in converting" electrical pulsations y into mechanical vibra-y tion and sound waves,- and '.ficonversely ,of

converting sound waves and I'necl1anical-vi-k Y 25 hrations into alternating' electric currents, is unusually high, to provide such a device in which there arenoV movable ormlexi; ble connections to get out of order;l and to provide a magnetic system which takes a.

30 veriv small amount of field current.

My invention may beclearly understood by reference to the accompanying schematic drawing in which 1.--1 represents an iron core, preferably laminated,"with pole pieces 2 and, 3-is atlexible iron ermatureheld in place in th'yoke at its outer-endedl and 4', and clearing the pole pieces` atits center by small air gaps 5 and 5. taround the the operating coils, 8 iu diaphragm, 9 is a vlink connecting diaphragm 81 to armature 3, and 10 is a hole through pole' piece 2 for link 9 to pass through,

46 AThe operation oflthe device is as follows:

the i-leld l wires are connected to a suitable source of direct current and the pole tips .2 andiQ" become very -stronglymagnetized N. and S as is shownin the drawing.

5.0 New when the alternatng operating current is connected to the armature wires, the center 'of armature 'becomes magnetized alternately N and S once for each alterna.; tion ci the operating current. Then the li center ci the armature is N, the armature pole pieces are field coils 6 :s111627 and 7' 40 around the armature but not touching it are rexss'aealeanovember zo, 1924.' 'serial lo. 751,190.

' isgsitron'gly rcpclled from the strong N lield l pole and at the saine time is strongl at tracted by thestrong S field pole, an this "results in the armaturespringi downward nearer pole 2 than polcQ', anl this down wai-d vmotion is transmitted through link 9 to diaphragm 8 and then to the air. Similarly when the center'ofthe armature is S, diaphragm 8 is pushed u wardly, which causes a' compression half o a sound wave to beformed.. Conversely, when sound waves strike diaphragm 8 armature 3 is 'madeto vibrate which .causes an alternating flux toiiow through the armature iron .inside of armature coils r(and 7.', and this induces an E. M. F. in the armature coils in accordance vwith the sound waves, and vhence the device can be used as a transmitter.

The great efficiency of the device as a loud spealfercomes from the fact that. there is such a direct interaction between the' strong fieldfiux and the armature flux right at the point off-the armature where the `torce' is transmitted tothe diaphragm, from there being .paths of Such lowvreluctance for both the field 'ux and armature flux as is pos sible by this design. :1nd from the fact that the whole core; may be laminated, thereby doing away with most of the eddy current losses. The field flux density is kept relatively low `sio that the core offers a good ei n/ieable return path for the Iarmature .uxx The air aps 5 and 5f 'are made short also to keep e reluctvice low, but allow pleut of'room for vibration of amature 3. o field flux flows through the 'armature and this leaves the amature in a very.F permeable condition for the .alternating larmature ux. I i v 4 It y-niight be .thought that one of the field ils could be eliminated and twice the number of ampere turns put on the remaining coil without impairing the operation of the device,but this is not thecase since the one field coil would act as a short circuited sec ondary coil to the alternating armature flux.'

When two field coils of equal numbereof turns ar'e ,used voltage induced in each coilvis 1n the .opposite direction e7) that by the combination of thev two coils in series, no induced alten `nating current flows in the field circuit. .One armature -coil tho,

and that end of the ,armature that was insideof this coil, could be eliminated 'without destroying the ho, 'as in the drawing, theA to the diaphragm.

princi le of this invention, but would reduce the e ciency somewhat.

Having thus described. my invention, so that anyone skilled in the Yart pertaining thereto can make and use the same, I claim:

1. In an electrical sound reproducing ap` paratus, the cbmbination of a shell type laminated core with the center part divided into' two poles with an air gap between' them, a field coil on each pole the two being connected in series and arrangedto 1nag' ole S,

in the part of the armature b'etwcen the field poles, a diaphragim andl a connecting lnl; to transmit the vibrations of the'l armature 2. In anapparatus used electrical variations into Yilnfations and" sound waves, or sound waves and vibrations into electrical "ariations, a combination consistingl of a laminated 'iron core W' h two Held o les which are Amagnetized ,N and S bya C. electric current through two field coils connected in series, an iron armature, a movable part of which plies in the air gap between the two field poles and -part of which is magnetically close or co'nnectid to the neutral part of the core yoke, arma# ture coils around/the part or parts of. the armature extendingr from the yoke to the. air gap between the field poles, and a link to connect. the movable part of the armaturc to the diaphragm or other vibration recording or producing apparatus. i

` 3. In an electrical sound reproducingr ap paratus'the combination of a magnet el@v ment having yokes and a center part divided `way that the center of the armature li A vbetween the two: above noted olcsarmai-l `least two surrounding yokes, an iron arn1a- J` tare, amovable-part of which plies in :the

to convert' audio* into two poles with un air gap between them, one a south pole sind one a north poleg'a flexible armature magnetically connected to the yokee ofthe magnet element in such tgure coilsaround each end ot tie annatulre and connected so that both produce the. same magnetic polarity in the part of the annature between' the -two,said poles, a 'dim l phragm, and connecting means to transmit the vibrations of the armature to thc da-l phragm. .f

4. In afn apparatus used to convert audio electrical variations into` vibrations and sound waves or sound wavesV and vibrationfJ into electrical variations, a. combination conl sisting of a magnet element havingr opposed interspacednorth( and south poles, and at air' gap between the two poles, and part di which is magnetically close or connectcdt, the neutral part of the yokes, armature c around the parts of the armature extending! fromthe yoke to the air gap between the poles, at opposite sidesof the poles `and means to connect the movable part of the armature toa diaphragm or other vihratta'x recording or producing member.

5. In a radio loud speaker, the combination of magnet 'element formed of E shaped sections facing each other with the central arms 'terminating in north and lsouth poles respectively, with an air gap betweenthem, a resilient armature located' with its central pont insaid air gap and lwith its endey Vmountedclose to thc median points o f the 

